Electric fuse



June 16, 1931. w. G. HARTWIG ELECTRIC FUSE Filed April 26, 1928 mam, G;

Patented June 16, 1931 UNITED STATES PATENT OFFICE- 1 WILLIAM G. HARTWIG, OF CHICAGO, ILLINOIS, ASSIGNOR TO RAILWAY UTILITY COM- PANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS ELEc'rnic rusr:

Application filed April 26,

This invention relates to improvements in electric fuses adapted for use in safeguarding electrical circuits and the purpose of the invention is to provide a simple and eflicient form of fuse particularly adapted for use in causing a circuit to open upon the passage of a relatively small maximum current. One object of the invention is to provide a fuse having the advantages of dependability and long life by reason of the omission in its construction of any salts and acids such as are usually employed for soldering the fusible elements employed in fuse construction. A further object of the invention is to provide a fusible element having a reinforcement which prevents breakage thereof due to jars and shocks encountered when in use or when being transported. A further object of the invention is to provide a fuse having a fusible element which is reinforced throughout its length by a fibrous strip adhering thereto. Still another object of the invention is to provide a fuse comprising a plurality of parts which are secured together by clamping frictional engagement without the use of any auxiliary fastening means. Other objects relate to various features of construction and arrangement which will appear more fully hereinafter.

The nature of the invention will be underment 13, as shown in Figs; 2 and 5, and after stood from the following specification taken with the accompanying drawings in which one embodiment is illustrated. In the draw- 1ngs,-

Fig. 1 shows a longitudinal axial section through the completed fuse embodying the, features of the present invention;

Fig. 2 shows a detail section taken on the line 22 of Fig. 1; v

Fig. 3 shows a perspective View of the" insulating tube embodied in the complete fuse shown in Fig. 1; Fig. 4 shows a perspective view of one of the metal end caps of the fuse; Fig. 5 shows a perspective view of the 1928. Serial No. 272,965.

fusible element assembled in the two metal clamping members by which it is mounted in the insulating tube; and 1 Fig. 6 is a cross sectlon, on an enlarged scale, through the fusible element,show1ng 11, a fusible element 13, and a pair of clamp-.,

ing members 14 which hold the fusible ele ment 13 in place, within the tube ,11. The clamps 14 are made upof copper strips which arebent to have the form shown particularly in Fig. 5, comprising a pairof par; 'allel arms, 14 which are joined togetherat their lowerends as: shown-at 14 and which I are connected at their upper endsjwith' the outwardly directed curved wings'14 having a curvature corresponding to; that of, the

formed between the arms near the clamping member and this slotis adapted 'to be engaged by one end portion of the fusible elethe fusible elementhas been inserted in the slots' of the two clamping members, these clamping members are caused to engage the slots 16 which extend inwardly from each end of the tube 11. The width ofthe slot 16 p the curved wings 14 lie in close contact with the outer surfaces of the tube 11,after which the cup-shapedcopper caps or ferrules 12 are slipped over the ends of the tube 11 to enclose the clamping members 14 and make ,outer surfaceof the tube 11k A slot15fis electrical contact therewith so that when the fuse is inserted in a fuse box, in the usual manner, the caps 12 will make electrical contact with the clips of the fuse box and thus connect the fusible element 13 in the circuit.

The fusible element 13 is preferably made up in the form shown in Fig. 6 where it is illustrated as comprising a. strip 13" of metallic foil, such as tin or aluminum, which is backed up with a strip 13" of reinforcing material such as thin, strong-grained paper. This strip 13" is secured to the strip 13 of metal foil by a suitable cement or glue so that the two strips adhere firmly to each other. In this way the metallic foil 13 is reinforced throughout its length and both strips are preferably of uniform cross section throughout so that no one point of the fuse is weaker than another. In this way the member 13 has great strength, even when the fusible element is one adapted to melt upon the passage of a relatively small current, for example, from one-tenth to one-half an ampere, and it permits the use of a cartridge type of fuse where protection at such small currents is desired. The paper backing for the fusible element permits a more accurate calibration of the fuse than would otherwise be possible and effectively prevents the breaking of the fuse under jars or shocks which are encountered during shipment of the fuse.

Although one form, of the invention has been shown and described by way of illustration, it will be understood that it may be constructed in various other forms within the scope of the appended claims.

I claim:

1. The combination in a fuse of an insulating tube having slots at the ends thereof, a clamping member detachably mounted in each of said slots, each clamping member comprising a reversely bent conducting member having a pair of parallel arms having side wings extending over the outer surface of said insulating tube, said arms of said clamping members engaging the ends of said fusible element, and cap members sea-ted over the ends of said tube to contact with said clamping members and thereby establish electrical connection with said fusible element.

2. A fuse comprising an insulating tube having a slot extending inwardly from each end thereof, a fusible element, a pair of clamping members each comprising a part arranged to grip said fusible element and to extend outwardly therefrom through said slot and another part extending circumferentially over said tube on the outer side of said slot, and cap members fixedly engaging the ends of said tube and contacting with the last named parts of said clamping members.

3. A fuse comprising an insulating tube having a single slot at each end thereof extending inwardly from the end of the tube, a fusible element, and a pair of clamping 7 bers extending over the ends of said tube and contacting with the outer parts of said clamping members.

In testimony whereof, I have subscribed my name.

lVILLIAlVI G. HARTVIG. 

